OLYMPIA, Wash. -- State Attorney General Bob Ferguson said Friday he is "cautiously optimistic" after President Donald Trump reportedly promised to protect the legal marijuana industry in states, but noted that the president "has demonstrated a willingness to go back on his word."

And Gov. Jay Inslee tweeted of the report, "This is welcome news, if true. We'll wait to read the fine print."

Inslee and Ferguson issued their statements after Republican Sen. Cory Gardner of Colorado announced Friday that Trump made the marijuana pledge to him in a Wednesday night conversation.

Gardner has been pushing to reverse a decision made by U.S. Attorney General Jeff Sessions in January that removed prohibitions that kept federal prosecutors from pursuing cases against people who were following pot laws in states such as Colorado that have legalized the drug.

Marijuana has been fully legalized in eight states, and 24 states allow some form of marijuana use.

"President Trump has assured me that he will support a federalism-based legislative solution to fix this states' rights issue once and for all," Gardner said in a statement.

White House spokeswoman Sarah Huckabee Sanders said Gardner's account was accurate and the president supported states' rights in the matter.

In Olympia, Ferguson said in a news release, "“I understand President Trump has offered his support for states to have the right to regulate marijuana and for legislation to enshrine this right in law. I am cautiously optimistic that the president appears to have heard the will of the people on this issue.

"But this president has demonstrated a willingness to go back on his word. Until there is a formal agreement protecting Washington’s well-regulated marijuana industry, I will continue to stand ready to defend it," Ferguson said.

Gardner hopes to introduce bipartisan legislation in Congress keeping the federal government from interfering in state marijuana markets.

Marijuana legalization advocates were ebullient.

"We may now be seeing the light at the end of the tunnel," said Mason Tvert, who spearheaded a 2012 ballot measure legalizing recreational marijuana in Colorado. "This is one more step toward ending the irrational policy of marijuana prohibition, not only in Colorado but throughout the country."

During the campaign, Trump said states should be able to chart their own course on marijuana. But Trump has also railed at the dangers of drug-related crime and suggested recreational marijuana should not be permitted.

When he selected Sessions, a former federal prosecutor and U.S. senator from Alabama, as his attorney general, marijuana supporters girded themselves for a crackdown. But Gardner said Sessions had promised him he'd do nothing to interfere with Colorado's robust marijuana market.

Gardner said he was blindsided when Sessions made his announcement in January regarding pot prosecutions.

In retaliation, Gardner used his power as a senator to prevent consideration of any nominees for the Department of Justice — an extraordinary step for a senator to use against an administration run by another member of his party.

Some of Gardner's fellow GOP senators groused at the impact of the hold, and Gardner allowed some nominees to proceed in a "good-faith" gesture last month. On Friday, he said he was fully releasing his holds on Department of Justice nominations.

The action came amid widespread speculation that Trump will remove Justice officials overseeing the Russia investigation. Replacements of any of those officials would require new nominations.

Gardner and the Department of Justice have been in discussions for months to get the holds lifted. Gardner has met with Sessions and Deputy Attorney General Rod Rosenstein, the official overseeing the Russia probe who has been the target of Trump's ire.